BIG CATS PLAN FOR AMERICA |Mark Northemail@example.com|08/27/05 at 18:31:19|Mark_North|xx|0|220.127.116.11|Lions, cheetahs and elephants may be introduced into North America after 13,000 years under adventurous new proposals.
Large tracts of the continent could be handed over to the animals to offset the threat of their extinction in current habitats.
Scientists say not only could the venues act as animal reserves but also huge tourist attractions.
The initiative is being championed by Cornell University in New York.
Writing in the science journal Nature, team leader Josh Donlan said: "Africa and parts of Asia are now the only places where megafauna are relatively intact.
"The loss of many of these species within this century seems likely.
"Given this risk of further extinction, re-wilding of North American sites carries global conservation implications."
The scientists believe that the native North American pronghorn antelope's turn of speed may be due in part to the existence of the cheetah alongside its ancestors centuries ago.
They said large mammals were common across all continents during the Pleistocene age which lasted from about 1.65 million to 10,000 years ago when a wipeout hit North America the hardest.
During the first phase, Asian asses and the Przewalski horse would be reintroduced, followed by big cats and elephants to private parks in the second.